Scientific Notes. 
428 
[July, 
in any way interfering with its stability. The stage is also somewhat lower, 
rendering manipulation more convenient. The fine adjustment no longer ads 
upon an adapter in the nozzle, but bears diredly upon a slide carrying the 
whole body of the instrument. This contrivance gives great accuracy and 
steadiness of movement, and prevents the alteration of magnifying power in- 
separable from the older contrivance, and which gives great trouble when 
micrometers are in use. The stage has been simplified and rendered extremely 
thin, without sacrificing any useful movement. Below the stage the American 
swinging bar has been adopted, allowing the mirror, with the whole of the very 
simple yet effedive sub-stage apparatus, to be moved out of centre, even to 
the extent of being placed above the stage, while its accurate placing in the 
axes of the microscope when required is secured by means of a clamping- 
screw. The scope offered for the employment of great variety of oblique 
illumination by simple contrivances, such as spare objedives and eye-pieces 
used as condensers, will suggest itself, while the microscope will still carry 
every other kind of illuminator. Notwithstanding these advantages, the sim- 
plification in construdion has enabled the stand to be made at 25 per cent 
less cost than its predecessor. 
The adjustment collar, a source of much trouble to the less expert observers 
with high powers of large angular aperture, has been dispensed with in an 
objedive construded by Herr Zeiss, of Jena, at the suggestion of Mr. J. W. 
Stephenson, F.R.A.S., from the formula of Prof. Abbe. The objedive is on 
the immersion principle, and depends for its properties upon a fluid being em- 
ployed having the same refradion and dispersion as crown glass. After many 
trials it was found that oil of cedar-wood gave perfed definition with oblique 
light, but for central illumination was greatly improved by the addition of 
one-fourth or one-fifth of oil of fennel seed ( 01 . Fceniculi). The objedive 
has a balsam angle of 113 0 = D25 numerical aperture.* It has a large working 
distance. The space between the front lens and the objed is o‘02, which 
gives a working distance 0 012 for o'ooS cover-glass, o’oi6 for o’oo/j., and so 
on. Its power is rather more than one-ninth, and, having component lenses 
throughout the combination larger than in other objedives of the same power, 
it transmits more light. 
Two numbers of the “ Journal of the Royal Microscopical Society ” have 
been issued. Although the amount of printed matter is less than under the 
former arrangement, and the issue is only bi-monthly instead of monthly, the 
Fellows of the Society are decidedly gainers by the change, as— the Council 
now having entire control over the publication of their Transadions— a quan- 
tity of controversial matter, which detraded greatly from the status of the 
former journal, is rigidly excluded. Besides papers read before the Society, 
the Journal contains a well-compiled abstrad of Microscopy from foreign and 
other sources. It also contains a list of articles on microscopical subjeds, 
published in various British and foreign periodicals. 
The Atlas of Colorado, issued by the United States Geological Survey of 
the Territories under Prof. F. V. Flayden, embodies the results of the geo- 
logical and geographical work of the Survey during the years from 1873 to 
1876 inclusive. This atlas will contain the following maps : — 1st. A general 
drainage map of Colorado on a scale of twelve miles to the inch. 2nd. An 
economic map of the same region, having as its basis the above-mentioned 
drainage map. This map will indicate the areas of arable, pasture, timber, 
coal, mineral, and desert land in as great detail as possible on the scale. 3rd. 
A general geological map on which the areas covered by the principal for- 
mations will be shown. The drainage map will form the basis for this also. 
4th. A map showing the scheme of the primary triangulation in the State. 
Scale twelve miles to the inch. 5th. Six topographical sheets, showing the 
same area as that covered by the general drainage map, but in much more 
* Numerical aperture is product of the sine of the semi-aperture with the refradtive index 
of the medium in which the observation is made ( vide “ Description of Professor Abbe’s 
Apertometer,” Trans. Roy. Micr, Soc., Dec. 5, 1877, vol. i., p. 19). 
